The present application relates generally to gauges for clearance measurements, and more particularly to feeler or thickness gauges for automatically measuring and/or recording gaps or clearances.
Feeler or thickness gauges are heavily used in the industrial environment to measure precise gaps, clearance, spacing, positioning and like, such as in gas turbine, jet engine, calibration tools, etc., which is critical for regular maintenance, process optimization, and vibration mitigation. The feeler gauge itself is typically a hand-held measurement tool that includes several stacked, flat lengths or wires of steel or other relatively sturdy material of the same or different thicknesses called “blades” or “leaves.” The blades or leaves may be stacked in graduating thickness arrangement. The body of each leaf is typically of a substantially constant thickness (i.e., substantially parallel sides), and each leaf includes a thickness marking or other indication corresponding to the thickness of the particular leaf. For example, feeler gauges typically include two sets of measurements markings—one set of imperial units (typically measured in thousandths of an inch) and another set in metric units (typically measured in hundredths of a millimeter). Some feeler gauges include leaves that have a tapered edge to, for example, facilitate the insertion of the leaves between two adjacent components. Such gauges are commonly referred to as “taper feeler gauges.”
Both “regular” feeler gauges including leaves with flat tips and “taper” feeler gauges typically also include a casing or housing configured to rotatably couple the leaves in a stacked relationship. In particular, proximate one end of the leaves (the non-tapered end in taper feeler gauges) is a pin, rivet, hinge or other mechanism or configuration that allows for each leaf to independently rotate about a common axis of rotation. The casing or housing may also include a handle portion that surrounds the exposed sides of the “top” and “bottom” leaves. In such embodiments, the leaves can be rotated or pivoted about the axis of rotation so that all of the leaves are in a stacked, aligned orientation and positioned within the handle portion. Similarly, from such a “home” orientation one or more of the leaves can be rotated out from the handle and into an “extended” position.
Although the leaves are relatively sturdy and strong, the leaves and/or the hinge mechanism are sufficiently flexible so that leaves may be “bent” or otherwise deformed by a user such that a portion of two or more extended leaves distal from the axis of rotation are stacked together in an abutting relationship. For example, several non-adjacent leaves can be extended from the handle portion, if present, and substantially aligned, and then compressed or otherwise caused to be deformed such that at least the portions of the leaves adjacent the distal tips thereof are tightly stacked together in an abutting relationship to for an overall thickness. Stated differently, the leaves and/or the hinge mechanism is/are configured such that the space or gap between substantially aligned, non-adjacent, extended leaves can be reduced and substantially eliminated such that the substantially aligned extended leaves lie alongside each other. In this manner, differing combinations of the leaves of a feeler gauge can be rotated into an extended position such that they are spaced from the handle portion of the housing or casing (if present) and deformed so that they are “stacked” or otherwise combined to form a single extended “measuring blade.” Thereby, a “measuring blade” may be either a single extended leaf or a combination of extended stacked leaves.
In use, individual or differing combinations of extended leaves can be used to form “measuring blades” of varying thicknesses to measure tolerances, point gaps or any other critical spaces, gaps or clearances. For example, individual leaves can be sequentially extended and, at least attempted to be, inserted into a clearance or space between components depending upon the fit, or lack thereof, within the clearance. As another example, if a particular combination of stacked, extended leaves results in a measuring blade with a thickness that does not fit within a particular clearance between components (i.e., the tip of the measuring blade cannot be inserted in the clearance or space), one of the blades can be retracted and, thereby, the measuring blade thickness decreased. The user of the feeler gauge can then attempt to insert the new thinner measuring blade combination between the components. If the new thinner measuring blade can be inserted within the clearance, but includes a significant gap or spacing between the measuring blade and the components (i.e., fits too loosely), another leaf can be extended and a new thicker measuring blade formed. The new thicker measuring blade can then be retested for fit within the clearance between the components. Using such a trial-and-error method a measuring blade with a thickness that snuggly fits within, and thereby substantially corresponds to, the clearance between the components can ultimately be achieved. It is noted that the trial and error process of a feeler gauge utilizes the “feel” of the user to a significant degree. Experienced feeler gauge technicians have developed skills and know-how gained through experience and training to accurately use a feeler gauge.
Once a user has achieved a particular “measuring blade” with a thickness that substantially corresponds to a particular clearance, spacing or gap, the thickness indication provided on each of the individual leaves comprising the measuring blade can be manually read by the user, manually summed (if multiple leaves were used) and manually recorded to determine the numerical thickness or size of the particular clearance. The nature of current feeler gauges dictates such a manual measurement determination process. In fact, under typical current practices two workers are often required to perform a measurement with a feeler gauge: one worker physically handles the gauge and takes the measurement determination via a particular measurement blade, and the other worker records the measurement with respect to an indication of the particular clearance being measured. One of the workers must also have manually summed the individual blades or leaves forming the measuring blade to thereby make the gap or clearance measurement (if multiple leaves were used). Human-induced error is therefore ineluctable during this process, which thereby requires time consuming measurement repetition and, occasionally, disastrous improper alignment, adjustment or positioning of components.
Accordingly, it would be desirable to reduce or substantially eliminate the manual steps involved in determining and recording a gap or clearance measurement using a feeler gauge after a particular set of measurement leaves or blades is determined by a user (e.g., a skilled technician) to correspond to the size of the particular gap or clearance being measured. Such a measuring system should be highly accurate, efficient and allow for more objective determinations.